Can someone please help me with the specifics on how to build forts in BoA/WiA? I can't seem to find it in the manual or on this forum. I seem to recall seeing somewhere that you need a combination of supply units and artillery for the special "Build Fort" special order to become available. Specifically, I'm trying to rebuild a "new" Ft. Dusquesne. I captured it but before the French left, they burned it. There is still a depot there. Does that matter somehow?

Your are correct, you need one supply wagon and one artillery, but each must have four elements. If you have enough supply or artillery but in different units, combine them.Depots do not help at all in building the fort.